For measuring various process variables in liquid media, sensor arrangements are usually used, which are immersed in the liquid medium. Such sensor arrangements are, as is presented in FIG. 1, preferably composed of a double-walled tubular housing 2 and a long, extended sensor 3 made from glass, synthetic material or metal, which is arranged within the tubular housing 2 and on whose tip a sensitive element 5 is secured. In such case, the tubular housing 2 extends over the sensitive element, 5 and is sealed below by the sensitive element 5. The tubular housing 2 is generally referred to as an immersion tube, since an end of this immersion tube is in contact with the process medium. Through two traversing, oppositely positioned openings 6 on the end of the immersion tube extending into the measured medium, the process medium enters into the interior of the immersion tube, and comes there in contact with the sensitive element 5.
In order to clean or to recalibrate the sensitive element, the entire sensor arrangement with the immersion tube and the sensor body is translated out of the process medium and into a rinsing chamber. In such case, a large amount of process medium is brought along and into the rinsing chamber, which leads to contamination, and especially always proves disadvantageous, whenever the sensitive element should be newly calibrated, since, in this case, the rinsing chamber must first be cleaned of the process medium using a large amount of washing or rinsing medium before a calibration medium can be introduced.